Browsing by Author "Koomson, Bennetta"

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    Anthropogenic Sources and Risk Assessment of Heavy Metals in Mine Soils: A Case Study of Bontesso in Amansie West District of Ghana
    (Journal of Chemistry, 2023-11-16) Baah, Douglas Siaw; Gikunoo, Emmanuel; Arthur, Emmanuel Kwesi; Agyemang, Frank Ofori; Foli, Gordon; Koomson, Bennetta; Opoku, Philipa
    Contamination of the environmental receptors with heavy metals due to mining is a major topical environmental issue in Ghana. *is research investigates the possible ecological and human health risks of heavy metal impacts due to mining in the Amansie West District in Ghana. A total of 18 soil samples were taken from the Bontesso illegal mining site in the district and analyzed for the levels of arsenic (As), cadmium (Cd), copper (Cu), nickel (Ni), and lead (Pb) using atomic absorption spectrometry (AAS). From principal component analysis, cluster analysis, and correlation coe8cient analysis, the metals are derived from multiple sources, with substantial levels of correlations. Using geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (Cd), pollution load index (PLI), ecological risk index (Er), and noncarcinogenic and carcinogenic risks, respectively, the impacts of As (12.2 mg/kg) and Cd (1.3 mg/kg) are above the WHO stipulated limit. Findings for pollution indices indicate moderate contamination, while HQ< 1 for inhalation and dermal exposure route, except for ingestion which is HQ> 1. Based on the USEPA standard, the carcinogenic risk of the pollutants for humans is higher than the range of 1 × 10−6 to 1 × 10−4. Furthermore, the ingestion route represents the highest contributor to cancer risk with arsenic posing the greatest risk. *e results so far suggest that chemical components gradually accumulate and thus emphasize the importance of implementing the necessary mitigation methods to minimize the impacts of illegal mining activities in the study area.
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    Arsenic Adsorption by Some Iron Oxide Minerals: Influence of Interfacial Chemistry
    (Ghana Mining Journal, 2020-12-12) Koomson, Bennetta; Asiam, Elias Kwasi
    The dramatic increase in hydrometallurgical extraction of gold from arsenic bearing gold ores has inevitably resulted in the release of arsenic into the environment worldwide. Residual arsenic minerals in tailings storage facilities can be oxidised and mobilise arsenic into the environment. This can contaminate soils, ground and surface waters and eventually biota. In spite of well-established technologies and recent advances in arsenic remediation, there are limited knowledge and understanding of the iron oxide substrate (goethite, hematite and magnetite) mineralogy and the fate of arsenic on the surface charge of these iron oxide substrates in an aqueous media during adsorption. The aim of the present study was to investigate the influence of interfacial chemistry on arsenic adsorption onto selected iron oxide particles to assist in developing a better understanding and new knowledge in arsenic removal from contaminated waters. Bulk mineralogy and partial chemical composition of selected iron oxide minerals were obtained using quantitative x-ray diffractometry (QXRD) and acid digestion followed by metal determination using inductively coupled plasma optical emission spectrometry (ICP-OES) respectively. Zeta Potential measurements involving iron oxide particles as arsenic adsorbents were carried out to elucidate the influence of interfacial chemistry on the adsorption behavior of arsenic from solution. The study confirmed that the iron oxide minerals were predominantly hematite, magnetite and goethite with goethite containing significant amounts of quartz. Arsenic adsorption was pH dependent and strongly influenced the zeta potential and isoelectric point (IEP) of the iron oxide particles. The zeta potential of all substrates studied was strongly positive at pH 2 but indicated a reversal at pH ~ > 9. The interaction between substrates, arsenic and its hydrolysable products resulted in significant decrease in the magnitude of zeta potential and change in IEP indicating specific adsorption.
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    Ascertaining the Quality of Water for Irrigation and Its Impact on Vegetable Quality: A Case Study Along the Bibini River in Kumasi.
    (Environment & Ecosystem Science (EES), 2021-06-23) Kyeame, Gifty; Koomson, Bennetta; Asiam, Elias Kwasi
    Farmers in peri-urban areas use diluted wastewater for irrigation. Over time, heavy metals may accumulate in agricultural soils and food crops causing health problems when consumed. Physicochemical, heavy metals (cadmium, lead and chromium) and microbial analysis of water, soil and vegetables were conducted to ascertain the quality of water and vegetables using standard methods. The results of the study showed that the water quality indicators; dissolved oxygen, biochemical oxygen demand and water temperature were not within the recommended standards of Ghana’s Environmental Protection Agency. The presence of heavy metals in the water, soil and vegetables were in the order of; soil (1.47 ± 0.017 of cadmium, 0.0019 ± 0.00011 of chromium and 0.541 ± 0.017 of lead) > vegetable (1.472 ± 0.044 of cadmium, 0.0020 ± 0.00010 of chromium and 0.474 ± 0.021 of lead) > water (0.068 ± 0.009 of cadmium, 0.0047 ± 0.00037 of chromium and 0.110 ± 0.014 of lead). Cadmium, chromium and lead concentrations in soil, vegetables and water varied significantly. Cadmium and lead concentrations as well as coliform counts in water and vegetables exceeded Food and Agriculture Organization/ World Health Organization’s maximum permissible levels. Soil samples from the control site showed almost negligible concentrations of heavy metals (0.00017 mg/kg of cadmium, 0.00014 mg/kg of chromium and 0.0011 mg/kg of lead) whereas farm sites had heavy metals as a result of long-term wastewater irrigation. Cadmium and lead concentrations in the water and vegetables makes them toxic and microbial populations of faecal coliform in water and lettuce indicated faecal contamination. Therefore, the quality of vegetables produced using the Bibini river is low and unsafe for human consumption.
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    Assessing The Acid Mine Drainage Potential of A Stockpiled Gold Bearing Sulphide Ore.
    (Earth Sciences Malaysia (ESMY), 2021-07-29) Koomson, Bennetta; Fosu, Shadrack; Brako, Blestmond Afrifa; Asiama, Elias Kwasi; Yanful, Ernest K.
    This work seeks to assess the acid mine drainage (AMD) potential of stockpiled sulphidic gold bearing ore that was left untreated for a period of four (4) years. The mineralogical composition of the stockpiled sulphidic gold ore was determined using X-Ray Diffractometry (XRD) and Reflected Light Microscope. The AMD potential and kinetic studies on the ore sample were determined using Acid Base Accounting (ABA) and Humidity Cell (ASTMD 5744). The XRD and microscope analyses showed that the gold ore contain arsenopyrite and pyrite as the major sulphide minerals. The ABA confirmed that the gold sulphide ore could be a potential source of AMD with respect to AMD marginal of safety if the ore is left untreated for a very long period. Humidity Cell kinetic analysis showed a possibility of mobilizing Arsenic (As) into the geoenvironment when there is a long period of oxidation of abandoned sulphide run-of-mine (ROM) ore.
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    Beneficiation of Iron Oxides from Cupola Furnace Slags for Arsenic Removal from Mine Tailings Decant Water
    (Ghana Mining Journal, 2022-06-20) Koomson, Bennetta; Koomson, John Ato; Asiam, Elias Kwasi
    Large volumes of ferrous metallurgical slags (FMS) are generated annually as waste materials from metal extraction, purification, casting and alloying processes worldwide. Some attempts have been made to use bulk FMS in metal precipitation and concrete works but little success has been achieved because of unstable precipitates and volume expansion of concrete structures. As a result, significant quantities of FMS are still disposed in landfills. This disposal leads to land conflicts and poor environmental practices. The present study focuses on the characterization and separation of iron oxide from selected bulk FMS (Cupola Furnace Slag - CFS) obtained from Ghana into constituent components for use as engineering materials. Quantitative X-ray diffractometry was used to determine the mineralogy of CFS. Iron oxide morphology and spot composition in the CFS were determined using scanning electron microscopy, combined with energy dispersive spectroscopy. The inductively coupled plasma-optical emission spectrometry was used to ascertain the chemical composition of CFS after acid digestion. Wet low intensity magnetic separation technique was employed for beneficiating iron oxides from the CFS. It is shown that the CFS is amorphous and consist of ferrous and non-ferrous material. Results of the investigation confirmed that ferrous materials in the slags can be separated using magnetic separation technique. The study further confirmed that fine grinding (- 75 μm) liberates the magnetic portions of the slag efficiently, and as such, they can be recovered using a low magnetic field. The recovery was 99.04 % and the concentrates obtained from the beneficiation process consist primarily of pigeonite, quartz, magnetite and jacobsite. The beneficiated concentrates have the capacity to adsorb arsenic from mine effluent. This study has demonstrated that, slags can be utilized as secondary resources rather than a waste.
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    Deforestation in forest-savannah transition zone of Ghana: Boabeng-Fiema monkey sanctuary
    (Global Ecology and Conservation, 2020-12-23) Amankwah, Afua Amponsah; Quaye-Ballard, Jonathan Arthur; Koomson, Bennetta; Amankwah, Richard Kwasi; Awotwi, Alfred; Kankam, Bright O.; Opuni-Frimpong, Nana Yeboaa; Baah, Douglas Siaw; Adu-Bredu, Stephen
    Forests provide many resources, ecosystem services and absorb carbon dioxide, which helps in climate regulation. In spite of the enormous benefits of forests, the issue of deforestation is still ongoing. There has been a continuous decline in forests globally and the forest area of Boabeng Fiema Monkey Sanctuary (BFMS) in Ghana is facing a similar threat. The aim of the study is to determine the different forest cover types and changes in the forest of BFMS. Satellite images for the years 1992, 1998, 2004, 2010, 2016 and 2018 were downloaded. Unsupervised and supervised classification were performed to determine the different forest cover types and remote sensing software was used to detect the changes in the forest cover. The forest cover was classified into six classes; closed forest, open forest, savannah woodland, savannah, farmlands and built-up area. Available data suggests that between 1992 and 2018, closed forest decreased by 242.19ha, open forest increased by 122.85 ha, savannah woodland increased by 7.47ha, savannah increased by 6.48 ha, farmland increased by 39.39ha and built-up area increased by 65.7ha. The changes in closed forest, open forest, farmland and built-up were all significant. Decreasing forest cover of BFMS is a threat to sustainable ecotourism since the forest serves as a habitat and food source to the monkeys. This research serves as guide to other researches aiming at determining forest cover changes in forest-savannah transition zones. In addition, the results have produced an inventory of the forest, which will help forest resource managers sustainably manage the forest.
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    Detoxification of lead and arsenic from galamsey polluted water using nano synthesized iron oxide from cupola furnace slag
    (Materials Chemistry and Physics, 2023-10-15) Koomson, John Ato; Koomson, Bennetta; Owusu, Clement; Agyemang, Frank Ofori
    Drinking of water polluted with heavy metals is a means by which heavy metals bio accumulate in the human body. The rise in galamsey (illegal mining) activities in Ghana has resulted in heavy metal pollution in most water bodies in the country. Above the permissible limits, these metals cause health issues such as cancer, brain damage, kidney damage and other respiratory diseases. Hence, a smart solution to this menace is urgently needed. In this study, iron oxides were recovered from cupola furnace slag by magnetic separation and froth flotation. The recovered iron oxide was modified using electrospinning with the aid of polyvinyl alcohol after which it was calcined and used as adsorbent to detoxify lead and arsenic from two galamsey polluted water bodies in Obuasi, Ghana. Samples of the adsorbent were characterized using X-ray Fluorescence (XRF), X-ray Diffractometry (XRD), Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscopy (SEM) and Brunauer-Emmer-Teller (BET) method. The highest recovery for iron oxide using magnetic separation was 99.42% and that of froth flotation was 90.64%. The recovered iron oxide used as adsorbent was composed 53.04% iron oxide, with major phases like magnetite, hematite, goethite and quartz. Moreover, the surface functional group were determined to be Fe–O and OH. Also, the calcined nano fibres which were spherical in shape with rough surfaces had a specific surface area of 1.1331 m2/g. The contaminated and detoxified water were also analyzed using Atomic absorption Spectroscopy (AAS). Both adsorbent (beneficiated iron oxide and calcined nano fibre) performed well in the adsorption process, with the recovered iron oxide having 97.33% maximum lead removal efficiency while an 81.00% maximum removal efficiency for arsenic. The calcined nano fibre had a maximum of 99.99% removal efficiency for lead and 88.40% maximum efficiency for arsenic. Additionally, the adsorption fits the Langmuirian isotherm model better than the Freundlich model, indicating mono layer coverage.
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    Heavy Metals Contamination and Distribution in Surface Water and Sediment of The Aboabo Stream, Ahafo Region, Ghana
    (Earth Sciences Malaysia (ESMY), 2021-05-11) Brobbey, Ebenezer Asante Boafo; Koomson, Bennetta; Agyemang, Frank Ofori
    Activities of illegal small-scale miners promote continual introduction of wide pollutants into the Aboabo stream. Their toxicity poses health threats to the inhabitants of Krapoo village in the Ahafo Region, Ghana. The study assesses the impacts of illegal small-scale mining activities on the water quality of the stream. Levels of physico-chemical and microbiological parameters were determined using standard methods. Samples of sediment, water and plant were acid-digested with aqua-regia. Total Arsenic and Total Cadmium were analysed using Flame Atomic Absorption Spectrophotometer (FLAAS) whiles Total Mercury was analysed using Cold Vapour Atomic Absorption Spectrophotometer (CV-AAS). Turbidity, faecal coliforms and E-coli readings exceeded permissible limit of 5NTU and 0MPN/100ml respectively by Ghana’s Environmental Protection Agency (GS 1212) and World Health Organisation (WHO). Temperature, Electrical Conductivity and pH values were within the limit of <30oC, 1500μs/cm and 6.5-85 respectively at both seasons. Total suspended solids readings at the midstream were higher than the permissible limit. However, levels of total dissolved solutes and dissolved oxygen recorded, were below the limit. The sediments were also heavily polluted with Mercury, Arsenic and Cadmium. Alchornea cordifolia, Chromolaena odorata and Spigella anthelmia growing within the stream were taken to assess their efficiency in removing the heavy metals from the stream. It was observed that the plants species had bioaccumulation factor (BF) greater than 1 for cadmium. Alchornea cordifolia was the only plant with BF greater than 1 for mercury. The plants species are potential hyper accumulators for mercury and cadmium hence are suitable for phytoremediation.
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    Molten salt synthesis of nitrogen-doped hierarchical porous carbon from plantain peels for high-performance supercapacitor
    (Journal of Electroanalytical Chemistry, 2022-09-01) Nanzumani, Nashiru Mahadeen; Agyemang, Frank Ofori; Mensah-Darkwa, Kwadwo; Appiah, Eugene Sefa; Arthur, Emmanuel Kwesi; Gikunoo, Emmanuel; Koomson, Bennetta; Jadhav, Amol R.; Raji, Akeem
    This work employs a non-corrosive and non-toxic molten salt combination of NaCl and KCl as an activation agent in an air environment to synthesize nitrogen-doped hierarchical porous carbon from plantain peels at 800 °C for supercapacitor application. Due to the synergistic effect of nitrogen doping, the synthesized nitrogen- doped activated unripe porous carbon (AUPN) has a hierarchical (micro-meso-macropores) porous structure and a high surface area of 959 m2/g, providing sufficient active sites for charge storage, rapid electrolyte and ionic mobility. X-ray diffraction and Raman spectroscopy analysis revealed the formation of a carbon product with a limited degree of graphitization and the crystallite size (La), which is valuable for evaluating the defects caused by nitrogen doping. In a three-electrode cell with a 6 M KOH electrolyte, AUPN recorded a specific capacitance of 550 F/g at 1 A/g. After 1000 cycles, capacitance retention was 99% at 4 A/g. Compared to other reported porous carbon materials, the overall electrochemical performance of AUPN is superior. This is due to the abundant nitrogen-doping, which introduces pseudocapacitance and increases the surface wettability of the porous carbon, resulting in a decrease in ionic-transport resistance. These findings indicate that this green and scalable technique is a potential synthesis method for producing porous carbon materials for energy storage applications.
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    Preliminary Study on the Use of Reverse Osmosis Brine and Mine Tailings as Cement Paste Mixtures for Mine Backfilling Application
    (Springer Nature, 2022-11-24) Opong, Rachael Wereko; Nsiah‑Baafi, Elsie; Andrews, Anthony; Koomson, Bennetta
    The processing of low-grade gold ores generates a significant volume of tailings and wastewater that impacts the environment. The treatment of wastewater using reverse osmosis (RO) produces brine as a by-product with high salinity levels. Improper disposal of mine wastes can significantly pollute water bodies and soils. A novel and sustainable method for managing, disposing, and handling these wastes is vital. The use of RO brine and mine tailings to produce cement paste mixtures for backfilling applications has been investigated. Sulfide gold mine tailings and RO brine were characterized, and cement paste backfill (CPB) mixtures were prepared by mixing varying proportions of cement and RO brine. The CPB cubes were cured for a specified number of days, and their physical and mechanical properties were determined. The results indicate a decrease in slump value with increasing cement content, whilst the slump increased with RO brine content. The compressive strength at 28 days increased with binder content reaching a maximum of 1.83 MPa using 50% RO brine. The CPB cubes produced with 50% RO brine and 12 wt.% cement possessed the required combination of fluidity and strength for mine backfilling applications.
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    Studies on Arsenic Release and its Mitigation from Tailings Dam Using Nanomagnetite Particles
    (Ghana Mining Journal, 2013-06) Koomson, Bennetta; Asiam, Elias Kwasi
    Knowledge of the geochemistry of As in tailings material after beneficiation of gold-bearing sulphidic ores is necessary to comprehend the nature, stability and mobilization of As into the geo-environment and its subsequent mitigation during storage. In this study, XRD combined with reflected light microscopy and SEM-EDX were employed to carry out studies on the mineralogical composition of As in a tailings material. Arsenic-rich solutions were generated from the tailings material using deionised water to ascertain As mobilisation. The remediation kinetics of the soluble As was carried out using nanomagnetite (Fe3O4). The XRD and SEM- EDX analyses showed that the major source of As in the tailings material is arsenopyrite (FeAsS). The study further confirmed that the residual As mineral in the tailings material is capable of decomposing during storage and can be subsequently mobilised into the geo-environment. It was established that nanomagnetite can efficiently remove As from tailings leachates; preferably at pH between 6 and 7 and Langmuir isotherm best described the sorption process while the Gibbs free energy of the sorption was found to be -12.1026 KJ/mol. Thus, nanomagnetite can be used to mitigate arsenic foot-prints from tailings dam.
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    Understanding the Mechanism of Arsenic Mobilisation and Behaviour in Tailings Dams
    (Ghana Mining Journal, 2017-06-20) Koomson, Bennetta; Asiam, Elias Kwasi; Skinner, William; Addai-Mensah, Jonas
    This study was carried out on leaching of tailings at 30 ᵒC and 40 ᵒC. The mineralogical and chemical composition of the tailings material were determined by Quantitative X-Ray Diffractometry (QXRD) and Scanning Electron Microscopy combined with Energy Dispersive Spectroscopy (SEM-EDAX). The study revealed that the tailings contain sulphides (arsenopyrite and pyrite) which can leach to produce arsenic (As) and other ions in solution. The acid released during leaching depends on the temperature of leaching. More acid was produced at higher temperature (40 ᵒC) than lower temperature (30 ᵒC). It was established that arsenic precipitation from solution was higher at higher temperature (40 ᵒC) than lower temperature (30 ᵒC). Mimicking the study in a typical tailings environment, it could be proposed that As mobilisation will be enhanced at lower temperature (30 ᵒC) than at higher temperature (40 ᵒC).